Question

(a) What do you mean by periodicity of properties of elements? (b) Arrange the following elements in their increasing metallic character. Br, Al, Mg, K (c) Determine the position of an element in periodic table whose atomic number is 32?

The periodic table of the elements, also known as the periodic table of the elements, arranges the chemical elements into rows ("periods") and columns ("groups"). It is an organizing icon of chemistry and is widely used in physics and other sciences. It is a depiction of the periodic law, which says that when the elements are arranged in order of their atomic numbers an approximate recurrence of their properties is evident. The table is divided into four roughly rectangular areas called blocks. Elements in the same group tend to show similar chemical characteristics. Vertical, horizontal and diagonal trends characterize the periodic table. Metallic character increases going down a group and decreases from left to right across a period. Nonmetallic character increases going from the bottom left of the periodic table to the top right. Elements with similar chemical properties generally fall into the same group in the periodic table, although in the f-block, and to some respect in the d-block, the elements in the same period tend to have similar properties, as well.

What is the cause of the periodicity in the properties of the elements? How do the following properties vary in (a) a group and (b) in a period: (i) electronegativity (ii) ionisation enthalpy (iii) Atomic size